1. Field of Invention
The present invention relates to methods of fabricating an array substrate and fabricating a filter substrate. More particularly, the present invention relates to methods of fabricating an active device array substrate and fabricating a color filter substrate of a liquid crystal display (LCD).
2. Description of Related Art
In current society, multimedia technology has been well developed, which mostly benefits from the development of semiconductor devices or display apparatuses. Among displays, liquid crystal displays, due to the superior characteristics of high picture quality, good space utilization, low power consumption, and radiation free, has gradually become the mainstream products in the market. A common LCD panel is mainly constituted of two substrates and a liquid crystal layer disposed between the two substrates. No matter for an active matrix LCD or a passive matrix LCD, two substrates must have alignment films, and the main function of the alignment films is aligning liquid crystal molecules to make the liquid crystal molecules assume a specific arrangement between the two substrates.
In a common twisted nematic (TN) LCD, the alignment film is fabricated after forming an alignment material layer, and an alignment process is performed by rubbing. More particularly, a roller with a rubbing cloth is used on the alignment material layer formed on a substrate to form a plurality of trenches on the surface of the alignment material layer, thereby forming an alignment film. As such, the liquid crystal molecules can be arranged along the trenches on the alignment film.
Another conventional alignment method makes use of an ion beam, which comprises using the ion beam to bombard the surface of the alignment material layer at a specific inclined angle, so as to achieve the alignment effect. That is, after forming an alignment material layer, a mask is formed by a lithography process to shield a portion of the region and expose other portions of the region. Then, the ion beam is irradiated to the surface of the alignment material layer along a specific direction. The details of the ion beam alignment method are disclosed in the patents such as U.S. Pat. Nos. 6,654,089, 6,313,896 and US 2003/0142257. However, the ion beam alignment method must employ a lithography process to form the mask, and due to the mask and exposure process, the process is complicated and has a high cost.
Besides the TN LCD, another common display is a multi-domain vertical alignment (MVA) LCD. In the MVA LCD with wide viewing angle, a plurality of protrusions or slit patterns are fabricated on the color filter substrate and/or thin film transistor array substrate. Through the protrusions and slit patterns, the liquid crystal molecules in different regions assume different arrangements, thereby achieving the purpose of wide viewing angle. However, electric field near the protrusions or slit patterns is non-uniform, thus easily resulting in the defect of mura. Moreover, the design of protrusions and slit patterns also reduces the transmittance and aperture ratio of the display panel.